Neuroanatomy, Cranial Nerve 1 (Olfactory)

The olfactory nerve is the first cranial nerve and is instrumental in our sense of smell. The olfactory nerve contains only afferent sensory nerve fibers and, like all cranial nerves, is paired. The olfactory nerve is the shortest cranial nerve, and along with the optic nerve is one of the only two cranial nerves that do not converge with the brainstem. Embryologically, the olfactory nerve is a derivative of the forebrain and is therefore considered a component of the central nervous system. The olfactory nerve is not myelinated by Schwann cells but rather is ensheathed by olfactory ensheathing glia. The olfactory nerves originate from the cell bodies of bipolar olfactory neurons in the olfactory epithelium, a specialized epithelial tissue found in the posterosuperior portion of each nasal cavity. Olfactory neurons give off projections apically towards the outside world and basally towards the olfactory bulb, the central hub, and coordinator of olfactory transmission. From the olfactory bulbs, olfactory information reaches the primary olfactory cortex via the olfactory tract. The primary olfactory cortex interacts with a variety of cortical and limbic structures via sophisticated pathways that allow the smell to become integrated with memory, emotions, and taste.